Process of preparing 2-isobutyl-1, 5-pentanediol



United States PROCESS OFIREPARING 2 -ISOBUTYL-1,5- PENTA'NEDIOL Kent C. Brannock, Kingsport, Tenn., assignor to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey No Drawing. Filed Nov. 2, 1959, Ser. No. 850,041

2 Claims. (Cl. 260-635) 4-formyl-4-(1-a1koxy alkyl) butauol .R may be an alkyl group of from 1 to 4 carbon atoms.

I have found that when R is R and R being alkyl and R being alkyl or hydrogen, the 2-alkoxy-3-(1-alkoxy alkyl) tetrahydropyran can be hydrolyzed with the loss of both OR groups by refluxing with acetic acid in the presence of a catalytic amount of an acid selected from the group consisting of mineral acids and strong organic acids having ionization constants of at least 1 10- to give 2-alkenyl-5- acetoxy-valeraldehyde, which can be hydrogenated to the corresponding 2-alkyl-1,5-pentanediol monoacetate. Saponification of the 2-alkyl-1,5-pentanediol monoacetate gives 2-alkyl-1,5-pentanediol. Examples of acids suitable for use as catalysts in the hydrolysis are p-toluenesulfonic acid, benzenesulfonic acid, naphthalenesnlfonic acid, sulfoacetic acid, sulfuric acid, sodium acid sulfate, potassium acid sulfate, phosphoric acid, oxalic acid, trifluoroacetic acid, trichloroacetic acid, dichloroacetic acid and the like.

My invention is illustrated, but not limited, by the following examples.

Example 1.A mixture of 238 g. of 2-ethoxy-3-(1- ethoxy-2-methyl-propyl)tetrahydropyran (prepared by the method of Paul and Tchelitscheft' from dihydropyran and isobutyraldehyde diethyl acetal), 240 g. of acetic acid, 50 ml. of benzene, and 0.3 g. of p-toluene sulfonic acid was refluxed under a Dean-Stark trap. No water was obtained until after 1% hours. By the end of 9% hours, 37.5 ml. of water had been separated. The re action mixture was poured slowly into a slurry of sodium 2,94,57l Patented Deco-13, #1960 bicarbonate in water-to remove the excess f acetic 'acid. The resulting mixture was extracted twicewith 1 00= ml. portions of ethyhacetate; and the combined'extracts were A hydrogenated over I R-aney nickel for --1-2- --hours,=-at 15 00 psi. and 150 C. The catalyst-"was removedhy-filtra .it-iona-nd the, filtrate'nvas distilled. After removal (if; the ethyl acetate there were obtained '26 g. of for'erun, B.P. 45-65 C. at 3-4 mm., and 108.5 g. of crude S-acetoxy- Z-isobutyl-l-pentanol, B.P. 115 C. at 3 mm. to 135 C. at 5 mm. Hg pressure. Saponification of this compound by conventional means, followed by distillation, gave 71 g. of 2-isobutyl-1,5-pentanediol, B.P. 120 C. at 3 mm. to 132 C. at 4 mm., n 1.4578.

CH3 OCQH; CH1

h xy-3-(1-ethoxy-2-meth 1. p pyh-tetrahydropymn CHLC 0.0.0 H2.CHr-CH2.CH.CH2OH CHs(E-CHS H 2-lsobuty1-1,5-pentanedio1 monoacetate H0.0H2.CH2.CHL OH.CH2OH CH3( /-CH3 H 2-isobutyl-1,5-peutanedio1 Example 2.--The process described in Example 1 was repeated, except that 0.1 g. of concentrated sulfuric acid was substituted for the 0.3 g. of p-toluenesulfonic acid. 37 ml. of water had been separated at the end of 8 hours. Workup as in Example 1 gave 64 g. of Z-isobutyl-LS- pentanediol.

Example 3.The process described in Example 1 was repeated, except that the catalyst used Was 2 g. of potassium acid sulfate. 33 ml. of water was obtained after 20 hours, and workup gave g. of 2-iso-but ,'l-l,5-pentanediol.

Example 4.--Similarly, using 0.5 g. of oxalic acid as catalyst, 37 ml. of water was obtained in 12 hours, and workup gave g. of 2-isobutyl-1,S-pentanediol.

Example 5.--Similarly, using 0.25 g. of trifluoroacetic acid as catalyst, 38 ml. of water was obtained after 8 hours, and workup gave 62 g. of 2-isobutyl-1,5-pentane diol.

The process is not operative when more than one of the groups R R R is hydrogen. For example, an attempt to carry out the process using 2-ethoxy-3-(1-ethox'ybutyl) tetrahydropyran, obtained from dihydropyran and n-butyraldehyde diethyl acetal, gave only high-boiling, viscous products from which no pure compounds could be separated.

The 2-alkyl-l,5-pentanediols are useful in the manufacture of plastic polyesters. Some of their carboxylic acid esters are useful as plasticizers and as synthetic lubricants.

I claim:

1. A process of preparing Z-isobutyl-l,S-pentanediol,

3 which comprises hydrolyzing with acetic acid, in the presence of a catalytic amount of an acid selected from the group consisting of mineral acids and strong organic acids having ionization constants of at least 1x1D- 2- ethoxy-3-(l-ethoxy-Z-methyl-propyl)tetrahydropyran, to give a mixture of S-acetoxy-Z-isobutenyl-n-valeraldehydes, hydrogenating the reaction product to give 2-isobutyl-1,5- pentanediol monoacetate, and saponifying the 2-isobuty1- 1,5-pentanediol monoacetate.

2. A process of preparing Z-isObutyI-LS-pentanedid, 1o

which comprises hydrolyzing with acetic acid, in the presence of a catalytic amount of p-toluenesulfonic acid, 2' ethoxy-3-( l-ethoxy-2-methylpropyl) tetrahydropyran, to give a mixture of 5-acetoxy-2-isobutenyl-n-valeraldehydes, hydrogenating the reaction product to give 2-isobutyl-1,5- pentanediol monoacetate, and saponifying the 2-isobutyl-1,5-pentanediol monoacetate.

No references cited. 

1. A PROCESS OF PREPARING 2-ISOBUTYL-1,5-PENTANEDIOL, WHICH COMPRISES HYDORLYZING WITH ACETIC ACID, IN THE PRESENCE OF A CATALYTIC AMOUNT OF AN ACID SELECTED FROM THE GROUP CONSISTING OF MINERAL ACIDS AND STRONG ORGANIC ACIDS HAVING IONIZATION CONSTANTS OF AT LEAST 1X10**-2, ETHOXY-3(1-ETHOXY-2-METHYL-PROPYL) TETRAHYDROPYRAN, TO GIVE A MIXTURE OF 5-ACETOXY-2-ISOBUTENYL-N-VALERALDEHYDES, HYDROGENATING THE REACTION PRODUCT TO GIVE 2-ISOBUTYL-1,5PENTANEDIOL MONOACETATE, AND SAPONIFYING THE 2-ISOBUTYL1,5-PENTANEDIOL MONOACETATE. 